Nuclear chemistry is a vast field yet not totally understandable the following presentation will provide u the basic concepts of its branches.

1. NUCLEAR CHEMISTRY
Presenter
Nofal Umair

2. Nuclear Chemistry
 Nuclear chemistry is the subfield of chemistry dealing
with radioactivity, nuclear processes and nuclear properties.
 We will discuss the following sub-fields
 Radiochemistry
 Nuclear Power
 Nuclear Reactions
 Applications

3. Radiochemistry
 Emission of subatomic particles or high-energy electromagnetic
radiation by nuclei
 Such atoms/isotopes said to be radioactive
 It is a spontaneous phenomena.
 We refer to these as radionuclide's.

4. Discovery Of Radioactivity
 Discovered in 1896 by Henry Becquerel.
 Marie Curie & hubby discovered two new elements,
both of which emitted uranic rays
 Polonium & Radium

5. Types of Radioactive Decay
 Rutherford and Curie found that emissions produced by nuclei
 Different types:
 Alpha decay
 Beta decay
 Gamma ray emission

6. 6
Alpha decay
 Has largest ionizing power
 Ability to ionize molecules & atoms due to largeness of -particle
 But has lowest penetrating power
 Ability to penetrate matter
 Skin, even air, protect against -particle radiation

7. 7
Beta decay
 Lower ionizing power than alpha particle
 But higher penetration power
 Requires sheet of metal or thick piece of wood to arrest
penetration
 more damage outside of body, but less in (alpha particle is
opposite)

8. 8
Gamma ray emission
 Electromagnetic radiation
 High-energy photons
 0
0
 No charge, no mass
 Usually emitted in conjunction with other radiation types
 Lowest ionizing power, highest penetrating power requires
several inches lead shielding

9. Figure 5.3: Ionizing power and penetrating power: an analogy.
© 2003 John Wiley and Sons Publishers

11. 11
Radioactive decay series

12. Predicting the mode of decay
1. High n/p ratio (too many neutrons; lie above band of stability) --
- undergoes beta decay
2. Low n/p ratio (neutron poor; lie below band of stability) ---
positron decay or electron capture
3. Heavy nuclides ( Z > 83) --- alpha decay

13. Nuclear Transmutations
 Transforming one element into another
 In 1919, Rutherford bombarded N-17 to make O-17
 The Joliot-Curie’s bombarded Al-27 to form P-30
 In ’30’s, devices needed that could accelerate particles to high
velocities:
 1. linear accelerator
 2. cyclotron

14. Trans-uranium elements
- Element with atomic numbers above 92
- Produced using artificial transmutations, either by:
a. alpha bombardment
b. neutron bombardment
c. bombardment from other nuclei
 Examples:
a.
b.
4He
2
Pu239
94
+ Cm242
96
1n
0
+
1n
0
U238
92
+ U239
92

15. Nuclear Energy
 There is a tremendous amount of energy stored in nuclei.
 Einstein’s famous equation, E = mc2, relates directly to the
calculation of this energy.
 In the types of chemical reactions we have encountered
previously, the amount of mass converted to energy has been
minimal.
 However, these energies are many thousands of times greater in
nuclear reactions.

16. Nuclear Fission
 Nuclear fission is the type of reaction carried out in nuclear
reactors
 Bombardment of the radioactive nuclide with a neutron starts the
process.
 Neutrons released in the transmutation strike other nuclei, causing
their decay and the production of more neutrons

17. Nuclear Fusion
 H-bonds utilize fusion (but needs high-temps to react because both
positively charged)
 As does the sun: 2
1H + 3
1H 4
2He + 1
0n
 10 x more energy/gram than fission
 Fusion would be a superior method of generating power.
 The good news is that the products of the reaction are not
radioactive.
 The bad news is that in order to achieve fusion, the material
must be in the plasma state at several million Kelvin's.

18. A flare ejected from the surface of the sun.
© 2003 John Wiley and Sons Publishers
Courtesy NASA

19. 19
More facts
 20 rem decreased white
blood cell count after
instantaneous exposure
 100-400 rem vomiting,
diarrhea, lesions, cancer-risk
increase
 500-1000 death w/in 2
months
 1000-2000 death w/in 2
weeks
 Above 2000 death w/in
hours

20. 20
Radiometric dating: radiocarbon
dating
 Devised in 1949 by Libby at University of
Chicago
 Age of artifacts, etc., revealed by
presence of C-14
 C-14 formed in upper atmosphere via:

14
7N + 1
0n 14
6C + 1
1H
 C-14 then decays back to N by -emission:
 Taken up by plants via 14CO2 & later
incorporated in animals
 Living organisms have same ratio of C-
14:C-12
 Once dead, no longer incorporating C-14
ratio decreases

21. Applications
 Medicine
 Chemotherapy
 Power pacemakers
 Diagnostic tracers
 Agriculture
 Irradiate food
 Pesticide
 Energy
 Fission
 Fusion

22. Images of human lungs obtained from a γ-ray scan.
© 2003 John Wiley and Sons Publishers
Courtesy CNRI/Phototake

23. A cancer patient receiving radiation therapy.
© 2003 John Wiley and Sons Publishers
Courtesy Kelley Culpepper/Transparencies, Inc.

24. Chemistry In Action: Food Irradiation
Dosage Effect
Up to 100 kilorad
Inhibits sprouting of potatoes, onions, garlics. Inactivates trichinae in
pork. Kills or prevents insects from reproducing in grains, fruits, and
vegetables.
100 – 1000 kilorads
Delays spoilage of meat poultry and fish. Reduces salmonella. Extends
shelf life of some fruit.
1000 to 10,000 kilorads
Sterilizes meat, poultry and fish. Kills insects and microorganisms in
spices and seasoning.